Aromatic polycarbonates are well known for their excellent properties. However it has always been a goal of workers in the area to prepare polycarbonates which retain as many of the excellent properties of aromatic polycarbonates to as great extent as possible, particularly the properties of bisphenol-A polycarbonate, while improving the melt flow of the polymer. A significant amount of the work in this area has focused on the introduction of certain comonomers into the structure to bring about such desired effects. For example copolyestercarbonates having aliphatic ester groupings have significantly improved flow but also display decreased thermal properties compared to the polycarbonate.
A novel copolycarbonate has been discovered which has substantially increased flow together with high thermal stability. This is achieved without introducing aliphatic repeating units into the polymer. The composition is a block copolymer and is prepared by standard interfacial techniques.